Exchange2007 (like Exchange 2003) doesn’t provide CatchAll functionality. CatchAll is the ability of an SMTP server to redirect messages to non-existing recipients to a specific address.

This CatchAllAgent is an Exchange 2007 Transport Agent. The CatchAllAgent can be configured to redirect the recipient address for unknown recipients to a ‘catchall’ address such that such messages end up in a dedicated mailbox. The configuration allows for multiple domains, but you can only specify a single target address for each of those domains.